1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly, to a semiconductor light emitting device.
2. Discussion of the Related Art
Generally, a semiconductor light emitting device has a light emitting region containing ultraviolet, blue, and green regions. In particular, a GaN-based semiconductor light emitting device may be used for an optical device of a blue/green light emitting diode (LED), and an electronic device with high speed switching and high output power performance such as a metal semiconductor field effect transistor (MESFET), a hetero junction field effect transistor (HEMT), etc.
FIG. 1 is a perspective view illustrating a structure of such a general semiconductor light emitting device.
As shown in FIG. 1, the semiconductor light emitting device 100 includes a substrate 110, a buffer layer 120, an undoped semiconductor layer 130, an N type semiconductor layer 140, an active layer 150, a P type semiconductor layer 160, a transparent electrode layer 170, a P type electrode 180 formed on the transparent electrode layer 170, and an N type electrode 190 formed on the N type semiconductor layer 140 exposed by partially etching the active layer 150 and the P type semiconductor layer 160. Although the active layer 150 and the P type semiconductor layer 160 are partially etched in FIG. 1, a part (upper portion) of the N type semiconductor layer may additionally be etched.
In the aforementioned semiconductor light emitting device 100, the transparent electrode layer 170 is generally formed using indium tin oxide (ITO) to desirably inject a current into the light emitting device 100 without current crowding when the light emitting device 100 is driven.
However, problems occur in that the ITO is expensive and contains indium, which is a rare metal and thus may be exhausted later.
Also, if the transparent electrode layer 170 is formed using the ITO, since light transmittance of the ITO is more than 90%, light may re-enter the light emitting device due to scattering with a phosphor or other material included in the light emitting device package, whereby the light may be lost. For this reason, a problem occurs in that light efficiency may be deteriorated in the semiconductor light emitting device package.